Huge tummy, doughy upper arms and feeling frumpy! Need wedding outfit for Feb!

[Nancery]

Please inspire me as I appear to still think I am a slender 21 year old...

I used to have a quirky fashion sense, and also used to be size ten. I like layers (cannot bear fitted, or 'control' underwear). If money were no object i would shop in Cabbages & Roses or Alice Temperley, but I can't afford either even if I wasn't too fat!

I have reasonable legs, but a roundish tummy (which I can't be arsed holding in) and, in my opinion, grim upper arms. I am a size 16. Im sick of looking at silk tunics from Monsoon (and already have one) and my sister is getting hitched at the end of Feb.

Help! Where can I start looking? Sick of feeling both fat and frumpy (am addressing the fat but it's a slow process!)

IME dressing a less than perfect frame is expensive if you don't want to look like 10lb sausage in 5lb casing.
FennWrightManson and LKBennet do flattering pieces. If they are a bit over budget M&S also do some clever shapewear clothing that don't feel like you are wearing shapewear.
Don't be put off by shops that appear to be for the more 'mature' customer. The clothes tend to be a better cut and style is what you make it.

Phase Eight? I think it's worth a look.

Thanks for your replies.
I will have a look at LK Bennett as only familiar with their shoes. It's very tricky to find something that both suits and flatters but also makes me feel like 'me' (or sort of the old me, within reason.)